What it is
Sorbitan isostearate is a nonionic emulsifier from the sorbitan ester family, made by esterifying sorbitan with isostearic acid. Like other sorbitan esters (the Spans), it has a low hydrophilic-lipophilic balance, which makes it well suited to water-in-oil emulsions and to stabilizing emollient creams. Besides binding oil and water phases, it helps disperse insoluble particles such as color pigments and mineral sunscreen actives like zinc oxide and titanium dioxide, and is often recommended for protective, baby-care, and general emollient creams.
Safety & warnings
Sorbitan isostearate is reported to have low irritation potential and only minimal pore-clogging potential, and it appears across a wide range of products including baby-care and protective creams, reflecting good general tolerability. As with any surfactant, very sensitive or reactive skin types may prefer to patch test a new product.
Origin & sourcing
It is a synthetic, plant-derivable ester. Sorbitan, its backbone, is produced by dehydrating sorbitol, a sugar alcohol, and is then esterified with isostearic acid, a branched C18 fatty acid, to give the finished nonionic surfactant.
History
Sorbitan isostearate belongs to the sorbitan ester class of nonionic surfactants commercialized under the Span name, which are made by esterifying sorbitan with fatty acids and are long established as emulsifiers in pharmaceuticals, cosmetics, and food. The broader family, including the related ethoxylated polysorbates, represents a large-volume category of commercial emulsifiers.
Questions everyone asks
What does sorbitan isostearate do in sunscreen?
It is an emulsifier that keeps the oil and water phases mixed and helps disperse pigments and mineral UV filters such as zinc oxide and titanium dioxide evenly.
What is it made from?
It is a sorbitan ester: sorbitan, derived from the sugar alcohol sorbitol, is combined with isostearic acid to make a nonionic emulsifier.
Is it gentle on skin?
It is reported to have low irritation and minimal comedogenic potential and is even recommended for baby-care and protective creams, so it is generally well tolerated.